China's official Purchasing Managers' Index (PMI) fell to 50.1 in April from 50.5 in March, below expectations that the PMI would be unchanged from March's reading. It pointed to continued but modest expansion despite a flurry of support measures. A reading above 50 indicates activity expanded.

A private business survey also showed China's factory activity cooled in April as export orders and employment decreased. The Caixin/Markit PMI fell to 50.2 from 50.8 in March, below expectations for a rise to 51.0.

Benchmark copper edged down 0.1 percent to $6,388 a tonne by 0739 GMT, while the most active copper contract on the Shanghai Futures Exchange (ShFE) ended up 0.1 percent to 48,930 yuan ($7,259) a tonne.

"PMI is below expectation but still in the expansion zone. We're not too worried about this because if you expand too much the government may scale back stimulus," said analyst Helen Lau of Argonaut Securities.

"China really does not want to see a super fast growth. They want to see a moderate growth," Lau said.

FUNDAMENTALS

* PRICES: London aluminium fell 0.5 percent, while nickel edged down 0.1 percent, zinc decreased 0.5 percent and lead was down 0.7 percent.

* SHANGHAI PRICES: The most active aluminium contract in Shanghai was almost flat at 14,175 yuan a tonne, nickel ended 0.2 percent lower while zinc closed up 0.9 percent.

* SHANGHAI STOCKS: Aluminium stocks in warehouses tracked by the ShFE &lt;AL-STX-SGH> dropped to 621,907 tonnes by Tuesday, its lowest since October 2017, while copper and zinc stocks &lt;CU-STX-SGH> &lt;ZN-STX-SGH> also fell.

* GLENCORE: Commodities trader Glencore lowered its full-year production target for copper on Tuesday as it reported a 7 percent drop in first-quarter output for the metal, hurt in part by severe flooding in Australia.

* NORSK HYDRO: Aluminium maker Norsk Hydro said a March cyber attack that paralysed its computer networks would cost the company up to 450 million Norwegian crowns ($52 million) in the first quarter.

* CHALCO: Aluminum Corp of China Ltd , known as Chalco, said its aluminium production fell by 6.9 percent year-on-year in the first quarter, underlining the impact low aluminium prices are having on its operations.

* RUSAL: Sales of value added products in the first quarter of United Company Rusal Plc, the world's top aluminium producer outside China, fell 44 percent from a year ago due to sanctions by the United States.

* TRADE TALKS: U.S. Treasury Secretary Steven Mnuchin said he hopes to make "substantial progress" with Chinese negotiators as he arrived in Beijing for further rounds of trade talks to end the trade war between the world's two largest economies.